Resonator Mod - worthwhile on Cat 3126 U295?

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Resonator Mod - worthwhile on Cat 3126 U295?

August 25, 2016, 03:05:08 pm

I've read many posts on several threads about performance improvements to be gained by replacing the stock muffler with a resonator. I can't seem to find any that mention having done this on the Cat 3126 engine. My concern is mainly due to several mentions of the relatively small size of some engines in comparison to the already large exhaust, resulting in a less impressive improvement than other engines. Has anyone done this to their Cat 3126 & did you see positive results?

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #1 – August 25, 2016, 03:19:18 pm

You are correctly evaluating it.

Muffler should have a PN on it. From that you can determine its CFM at a particular pressure.

Then give the Caterpillar RV Hotline a call with your engine serial number. They can tell you how close to minimum requirements your current muffler is.

That will tell you whether you will gain much.

Another source of information is Foretravel: As an example, if Foretravel fit the same muffler on your Caterpillar 3126 (a 7.2 liter engine) as they fit on the Cummins C engine (8.3 liter engine) it would be a waste of money, as you will not see much backpressure.

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #2 – August 25, 2016, 09:54:11 pm

Quote from: bdale – August 25, 2016, 03:05:08 pm

I've read many posts on several threads about performance improvements to be gained by replacing the stock muffler with a resonator. I can't seem to find any that mention having done this on the Cat 3126 engine. My concern is mainly due to several mentions of the relatively small size of some engines in comparison to the already large exhaust, resulting in a less impressive improvement than other engines. Has anyone done this to their Cat 3126 & did you see positive results?

I put a aero 5050xl on my 295 c7 3126 and did notice a slight increase in power. Turbo appeared to spool up faster and increased throttle response. Not much difference in sound. ran 5" from turbo back.

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #3 – August 25, 2016, 10:54:15 pm

Jim,

What size is the existing turbo output pipe?

What size was the original pipe from the turbo to the OEM muffler?

IIRC the aero 5050 is 5" input and 5" output, right?

Thanks,

Trent

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #4 – August 25, 2016, 11:18:30 pm

Quote from: TulsaTrent – August 25, 2016, 10:54:15 pm

Jim,

What size is the existing turbo output pipe?

What size was the original pipe from the turbo to the OEM muffler?

IIRC the aero 5050 is 5" input and 5" output, right?

Thanks,

Trent,
Two coaches ago so not the best memory of it, but think the turbo it self is 4"or 5" out, if it was 4, I bought a 4 to 5 inch adapter and then an 5" elbow to 5 inch flex pipe and used the 5 inch in and out resonator as final part. The resonator is polished so did not have to use a tip. Getting rid of the 50 lb muffler is worth a couple of hp all by itself. Depending on your coach layout, frees up quite a bit of space. I built a rack to hold gear in mine.
Jim

Trent

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #5 – August 26, 2016, 12:08:06 am

Not apples to apple, but here are testing results on a mechanical (no engine computer) 1994 Cummins 300 HP rated 8.3. (my current coach).

2/5/2010, 2/11/2010
Dyno 94 Bluebird BMC 37' Cummins 300 hp C8.3 turbo, Allison 3060 transmission.

Notes on Brazel's Water Brake style dyno:

Vehicle in direct drive (4th gear), Run up against rev limiter (2500 pm), hold pedal to floor as dyno consistently and evenly builds pressure using water as the resistant force against tires, Computer uses load cell to calculate torque and then horsepower as it "pulls" the engine down to the point where it has to downshift out of 1:1 ratio, full throttle during the entire test, let off when the vehicle kicks down out of 1:1 and at that stop the test.

Note: I watched an attached boost gauge today 2/11/10. At 2400/2500 rpm there is minimal boost, test starts, dyno load is induced, boost slowly climbs to max boost. No max boost on higher rpm range on test results below. Climbing a hill under load at high rpm in the real world equals more hp and torque than indicated on paper.

STOCK NELSON MUFFLER 2/5/2010
RPM>> 1400 1600 1800 2000 2200
HP>> 235 260 263 220 101
TQ>> 770 747 670 501 225

AEROTURBINE 4040XL MUFFLER 2/5/2010
RPM>> 1400 1600 1800 2000 2200
HP>> 245 266 270 230 119
TQ>> 783 760 689 545 249

GAIN (AEROTURBINE 4040XL COMPARED TO STOCK) 2/5/2010
RPM>> 1400 1600 1800 2000 2200
HP>> 10 6 7 10 18
TQ>> 13 13 19 44 24
-----------------------------------------------------------------------------------------------

INSTALL #10 FUEL PLATE FROM DIESEL PERFORMANCE w 4040XL 2/11/2010
RPM>> 1400 1600 1800 2000 2200
HP>> 318 331 317 230 119
TQ>> 1000 945 795 576 250

GAIN (adding fuel plate w aero 4040XL) 2/11/2010
RPM>> 1400 1600 1800 2000 2200
HP>> 73 65 47 0 0
TQ>> 217 185 106 31 1

TOTAL GAIN FROM STOCK 2/11/2010
RPM>> 1400 1600 1800 2000 2200
HP>> 83 71 54 10 19
TQ>> 230 198 125 75 25

Note: I watched an attached boost gauge today 2/11/10. At 2400/2500 rpm there is minimal boost, test starts, dyno load is induced, boost slowly climbs to max boost. No max boost on higher rpm range on test results above. Climbing a hill under load at high rpm in the real world equals more hp and torque than indicated on paper.

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #6 – August 26, 2016, 12:11:49 am

I did other Dyno tests, the smaller 4040 (4") resonator did better than the larger 5050 (5") on this displacement engine.

Original very long thread on WOG site. Brazel's Performance RV (BMC Service) - Wanderlodge Owners Group

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #7 – August 26, 2016, 12:25:13 am

There is several different schools of thought on backpressure on turbo'd diesels. Many think no restriction is the ticket, others think you must slow the flow. Most diesel drag racers believe the turbo is causing enough restriction already, and the path out out the turbo should be as large as possible.
Jim

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #8 – August 26, 2016, 03:00:14 am

Quote from: jcus – August 25, 2016, 11:18:30 pm

but think the turbo it self is 4"or 5" out, if it was 4, I bought a 4 to 5 inch adapter and then an 5" elbow to 5 inch flex pipe and used the 5 inch in and out resonator as final part.

If the turbo is only 4" out, what is the advantage of going up to 5" to a 5050, versus staying at 4" through a 4040?

Quote from: AC7880 – August 26, 2016, 12:11:49 am

I did other Dyno tests, the smaller 4040 (4") resonator did better than the larger 5050 (5") on this displacement engine.

Dan's results seem to imply the Aero 4040 results were actually better than the 5050 results.

Anyone have any experience or thoughts on why sticking with 4" pipes and an Aero 4040XL would not accomplish all we have talked about in going to a resonator? Obviously, it would also be cheaper and provide even more usable space left over.

Just thinkin' out loud,

Trent

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #9 – August 26, 2016, 08:35:39 am

Again, without knowing how restrictive (or not restrictive) the current muffler is, speculating on improvements is............

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #10 – August 26, 2016, 11:20:07 am

I stayed with the 4" Aero resonator on my 8.3 Cummins rather than going with the 5" do to possibly having negative effects with the turbine design.

Learn How It Works:
As the exhaust stream enters the Aero Turbine XL muffler, it expands to fill the cylindrical chamber. This expansion slows the exhaust stream, creating a lower pressure at the inlet which causes a scavenging effect similar to that of a header. The exhaust stream is then split via an airfoil cone with an orifice similar to a conical jet engine. The outer stream accelerates to a higher velocity as it flows around the cone and has a lower pressure than the core stream, which is traveling at a slower velocity, and a higher pressure. The two streams are reintroduced via perforations in the center core. The high pressure inner stream is initially drawn out of these perforations as the gas attempts to equalize the pressure differential between the two streams. As this occurs, the change in direction of the exhaust stream causes destructive interference, which deadens the sound. As the pressure is equalized towards the rear of the canister the exhaust gas is pushed back through the helically arranged perforations in the center core, which spin the exhaust stream, causing additional sound cancellation, reducing turbulence, and creating a vortex that enables the gas to more efficiently exit the muffler. This revolutionary design has been tested and proven to flow more exhaust gas than straight pipe!

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #11 – August 26, 2016, 12:53:10 pm

Regardless of whether or not you believe all the pseudo-scientific claims for improved performance, installing a aftermarket resonator/muffler does have a few verifiable benefits on almost any coach:

1. Lighter weight. As Colin Chapman preached "Simplify, and add lightness"...or something like that.

2. Less heat retaining mass = engine compartment cools down faster = cooler bedroom.

3. Easier access to the other engine stuff in the vicinity of the muffler. (on my 8.3 the oil filter, coolant filter, starter, hydraulic pump, etc.)

4. Easier access to the isolator panel (once again, at least on my U280).

5. Looks cool. (OK, this one is subjective, but a little bling never hurts anything, right?)

There's probably more...

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #12 – August 26, 2016, 12:58:44 pm

sounds cool....

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #13 – August 26, 2016, 01:23:33 pm

On 4" inlet outlet exhaust piping I'd stay with 4" resonator (especially on smaller displacement engines). Saves necking up and down. With 5" inlet / outlet I'd go with 5" resonator.

On my 8.3 liter with 4" piping, the 4" resonator out performed the 5" resonator by a bit.

On a larger displacement engine like the ISM I am willing to bet the 5" will out perform the 4" by a decent factor.

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #14 – August 26, 2016, 07:23:04 pm

Yup swapped out my old heavy muffer with 5 inch resonator and all that Chuck said and sounds way cool

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #15 – August 26, 2016, 08:07:37 pm

After reading these posts and Barry Beams article, I ordered the AT 5050 XL today and will put it in this winter.

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #16 – August 26, 2016, 08:48:10 pm

Quote from: craneman – August 26, 2016, 08:07:37 pm

After reading these posts and Barry Beams article, I ordered the AT 5050 XL today and will put it in this winter.

Installed same one last year. Seems to rev better. Slightly more power. Still testing. Noisier. But not that bad.

May convert the now empty compartment where the obese muffler was to a fire wood storage compartment

Changed it plus the fan controller to free up power and add mpg. Maybe

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #17 – August 26, 2016, 10:44:53 pm

I've seen the resonator on Ebay. Is there more specific information on the rest of the system (90 degree, 45 degree and 5" flex exhaust?) Where can we find these parts?

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #18 – August 26, 2016, 11:01:57 pm

Quote from: Sven and Kristi – August 26, 2016, 10:44:53 pm

I've seen the resonator on Ebay. Is there more specific information on the rest of the system (90 degree, 45 degree and 5" flex exhaust?) Where can we find these parts?

It will depend on how your year coach is set up, and the position you want to place the resonator. You will have to eyeball your setup and order what you need. The flexpipe allows you some wiggle room. You can get pipe, fittings, hangers etc from Ryder Fleet Products. or a local truck exhaust supply store.

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #19 – August 26, 2016, 11:35:16 pm

Quote from: Sven and Kristi – August 26, 2016, 10:44:53 pm

I've seen the resonator on Ebay. Is there more specific information on the rest of the system (90 degree, 45 degree and 5" flex exhaust?) Where can we find these parts?

There was a long (11 pages) thread that covered most of the questions you might have about this mod. If you are interested, grab a cup of your favorite beverage, find a comfortable chair, and read through it:

Resonator and muffler replacement

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #20 – August 27, 2016, 12:19:49 am

I can appreciate all of the secondary benefits that have been mentioned. For my coach, I don't have any issues with access to filters, isolator panels or anything else that has ever been an inconvenience with the stock exhaust. Less heat would be nice though. My primary goal is to realize a little bit more driveability, which is really the only complaint about my small Cat. It's pretty slow climbing even a slight grade and generally not as responsive as I would like. I plan to take Brett's advice and do the calcs to see exactly what cfm differential I can achieve from the upgrade but I'm not optimistic that it's going to show a significant benefit. Most anecdotal evidence that I have seen on RV's with my engine, mostly on other forums, indicates little or no improvement. The general theme seems to be a more significant improvement with larger displacement engines, less as engine size decreases. That puts me towards the bottom of the curve. If the stock exhaust is already over-sized, as I suspect it may be, that limits the improvement even more. If I can't justify the mod on performance alone I think that it will fall into the category of a repair opportunity when/if the current muffler ever fails.

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #21 – August 27, 2016, 12:44:20 am

Quote from: Sven and Kristi – August 26, 2016, 10:44:53 pm

I've seen the resonator on Ebay. Is there more specific information on the rest of the system (90 degree, 45 degree and 5" flex exhaust?) Where can we find these parts?

Quote from: Sven and Kristi – August 26, 2016, 10:44:53 pm

I've seen the resonator on Ebay. Is there more specific information on the rest of the system (90 degree, 45 degree and 5" flex exhaust?) Where can we find these parts?

Sven,
I think that only a few have followed my early lead, but I'm still convinced that if you are going to do it, it makes good sense to stick with a single metallurgical composition (304SS for all exhaust system components) to minimize the certainty of galvanic corrosion in the high temperature, chemically noxious environment that the exhaust system lives in. It isn't that difficult to do and the last time I saw her, the redesigned exhaust system was still great after seven years or so. I had not been able to reliably get four years out of the FT tailpipe and some of the hangers/clamps before that. Of course if you never drive in wet conditions, then it's not as critical, but then who can adhere to that mandate?
The following album, on the forum, contains some slides and a bill of materials for a Cummins 8.3, but it gives you some ideas on design sketch sequence, where to round up components and their relative costs.

http://www.foreforums.com/index.php?action=media;sa=album;in=210

I found all of the parts I needed just by calling a few truck service centers, JEGS (online), and a Peterbuilt sales and service center. All of the 304SS parts were easily found except for the 90 degree 4" short radius elbow, that I had to order from a truck Chrome and Radio shop. That took a few weeks to get in, but the rest I could have rounded up in less than an afternoon of running around. The only original parts that I re-used were the turbo clamp and the original two, 30 degree, 304 SS elbows. By rounding up your own parts, you can also insist on the stronger "Smooth Internal Flow" Flex pipe and the Heavy Duty sliding tailpipe clamps that "back" versus "pinch" the exhaust joints. These are all things that help with long term quality, and cost you less in the long run.
HTH,
Neal

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #22 – August 27, 2016, 12:46:19 am

My first inclination would be to research marine 3126 engines.

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #23 – August 27, 2016, 07:24:43 am

The stainless parts not only look better but also outlast throw her piping especially the flex. A piece of flex between the engine mounted parts and the frame mounted parts is a requirement if you rigid mount to the frame.

Re: Resonator Mod - worthwhile on Cat 3126 U295?

Reply #24 – August 27, 2016, 10:48:15 am

Quote from: Sven and Kristi – August 26, 2016, 10:44:53 pm

I've seen the resonator on Ebay. Is there more specific information on the rest of the system (90 degree, 45 degree and 5" flex exhaust?) Where can we find these parts?

Your model is similar to mine. I did a search for those parts and they were all available. I just need to make sure it is the same setup as Barry's

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